Over two million pieces of baggage are checked or carried onto civilian aircraft in the United States every day. This exposes the American traveler to a significant risk from concealed explosive devices. Although most carry-on baggage is scanned by x-ray scanners and trained personnel, scanners to detect explosives or explosive devices in checked baggage or cargo are limited by availability and ability. This invention relates to a device which checks individual pieces or batches of luggage, baggage, freight, goods, merchandise, cargo, and the like (hereafter referred to as "cargo") to detect the presence of concealed explosives, explosive devices, improvised bombs, and the like (hereafter referred to as "explosive devices") and simultaneously neutralizes such explosive devices by causing their premature detonation.
1. Detection of Concealed Explosives
Several categories of apparatus for detecting the presence of concealed explosive devices are known. A first category of apparatus, known as "explosives sniffers," operate by collecting a sample of air from the vicinity of the cargo and employing sensors which respond to the vapors emitted by certain types of explosive substances. Such apparatus include: U.S. Pat. No. 4,202,200 to Ellson, "Apparatus for Detecting Explosive Substances"; and U.S. Pat. No. 3,568,411 to Dravnicks et al., "Chemosensor Bomb Detection Device." A limitation of these explosives sniffer apparatus is that they are unable to detect explosive devices utilizing explosive substances which do not emit such characteristic vapors or when plastic, wax, glue, or other sealing agents have been used to contain the tell-tale vapors. A need therefore exists, for an explosive detection apparatus or method which detects concealed explosive devices which do not emit vapors.
A second category of apparatus for detecting concealed explosive devices, known as "nuclear detection" apparatus or "nuclear resonance detectors," operate by irradiating the cargo with beams of neutrons or other radiation which interact with specific elements such as nitrogen, chlorine, and hydrogen within the cargo and causes the release of characteristic secondary radiation which the apparatus then detects and analyzes to determine the presence explosive compounds. Such apparatus include: U.S. Pat. No. 5,078,952 to Gozani et al., "Multi-Sensor Explosive Detection System"; U.S. Pat. No. 5,006,299 to Gozani et al., "Explosive Detection System"; U.S. Pat. No. 4,980,901 to Miller, "Apparatus for and Methods of Detecting Common Explosive Materials"; and U.S. Pat. No. 4,941,162, to Vartsky, et al., "Method and System for Detection of Nitrogenous Explosives by Using Nuclear Resonance Absorption." The disadvantages of nuclear detection apparatus include their inability to detect explosives which do not emit characteristic secondary radiation such as improvised explosive devices of the type often utilized by terrorist entities. A need therefore exists, for an explosive detection apparatus or method which detects concealed improvised explosive devices or explosives which do not emit characteristic secondary radiation.
A third category of apparatus for detecting concealed explosive devices, known as "pressure cycling" apparatus, recognize that terrorist explosive devices may be designed to initiate or detonate only after experiencing multiple pressure "cycles" corresponding to the multiple altitude ascents and descents of an aircraft on different legs of its route. To counter the threat of such pressure sensitive devices, pressure cycling detection apparatus are known which simulate the multiple ascents and descents of an aircraft by repeatedly decreasing and increasing the pressure in a test chamber containing the cargo. An example of such a pressure cycling apparatus is disclosed in U.S. Pat. No. 5,274,356 to Taricco, "Methods and Apparatus for the Inspection of Air Cargo for Bombs." Taricco discloses repeatedly decreasing and increasing the pressure in a test chamber to initiate pressure sensitive explosive devices. Taricco further discloses using electromagnetic noise sensors to detect electromagnetic radiation characteristic of bomb timing devices which may be initiated by the pressure cycles. Disadvantages of the method and apparatus disclosed by Taricco include the limitation to the detection of pressure sensitive explosive devices which emit electromagnetic radiation upon initiation. A need therefore exists, for an explosive detection apparatus or method which detects concealed pressure sensitive explosive devices which do not emit electromagnetic radiation when initiated.
Furthermore, it is desirable for safety reasons in "pressure cycling" detection apparatus to test the cargo with as many pressure cycles as possible to decrease the likelihood that a concealed explosive device may be set for detonation after a greater number of pressure cycles than the number performed in the test. However, it is also desirable, for reasons of economy, to minimize the time required to test each batch of cargo. A need therefore exists, for an explosive detection apparatus or method which simulates a large number of aircraft ascent and decent cycles in a short period of time.
Known explosive detection apparatus of both the explosives sniffer and nuclear detector categories previously discussed function only to detect explosive substances. Such apparatus contain no means for neutralizing an explosive device once one has been detected. U.S. Pat. No. 5,274,356 to Taricco discloses that pressure sensitive explosive devices initiated and detected by pressure cycling apparatus can be allowed to self-detonate within the test chamber. However, since a terrorist explosive device may be equipped with a means for post-initiation delay, such passive neutralization methods may require an unacceptably long time to accomplish the necessary neutralization. A need therefore exists, for an explosive detection apparatus or method which detects concealed explosive devices and expediently neutralizes such explosive devices.
2. Neutralization of Explosive Devices
Most improvised explosive devices of the type used by terrorist entities are initiated by directing electrical current supplied by batteries or other sources through switches, relays, wires and the like to an electro-explosive device such as a blasting cap, squib, commercial detonator, or improvised detonator. These electro-explosive devices include at least one electrical ignition device disposed in ignition relationship with one or more heat sensitive explosive charges and are fired by passing a DC current through a high resistance filament wire or bridge of high electrical resistance which is in heat transferring contact with the first fire mixture. A sufficient flow of current heats the bridge wire to incandescence, thereby igniting the surrounding mixture, thereby detonating other charges. It is well known in the art that such electro-explosive devices are subject to unintended discharge by stray electromagnetic or electrostatic energy. Typically, blasting caps are most vulnerable to unintended detonation when subjected to short bursts of low frequency, high power energy in the radio frequency spectrum. Therefore, by directing bursts of high power, low frequency energy toward an explosive device, detonation of the device may be accomplished. Similarly, electromechanical relays and mechanical switches (including pressure sensitive switches) are vulnerable to unintended actuation when pulsed with strong magnetic fields applied externally to the device. Electromechanical relays, in particular, utilize ferrous metal armatures or reed switches which are typically actuated by solenoids or coils, thereby opening or closing electrical contacts. Therefore, a strong external magnetic field applied nearly parallel to the central axis of the coil or solenoid and opposite to the armature or reed switch will cause actuation of the relay contacts.
Other means of detonating improvised explosive devices include mechanical timers and pressure sensitive switches. By design, mechanical timers employ precision clock movements which are vulnerable to permanent damage when exposed to strong magnetic fields, thereby permanently deforming or dislodging parts of their movement, disabling the explosive device. Pressure sensitive switches, in order to detect slight changes in ambient pressure (which in an aircraft's pressurized cargo hold are less that 10 inches of mercury) must be precision devices in order to be effective. Therefore, any ferrous metal components of the pressure switch such as springs, diaphragms, or contacts are subject to permanent deformation and damage when exposed to strong magnetic fields.
High frequency energy of the type generated by magnetrons or klystrons may, when directed at explosive compounds in short pulses, produce sufficient heat in the material to cause detonation in the same manner as the filament wire of a blasting cap.
Additionally, devices for containing or redirecting explosions, known as detonation chambers, are widely known and used to protect surroundings by containment or redirection of explosions.
3. Additional Factors
While the use of concealed explosive device detectors is most commonly associated with aircraft and airports, increase public safety and confidence will result from the use of such apparatus and methods on all forms of public transportation and places of public accommodation. A need therefore exists, for an explosive detection method or apparatus which is suitable for use with aircraft, trains, ships, boats, busses, public buildings and the like.
Most airports and other enterprises with intensive cargo handling operations utilize automated baggage or cargo handing systems. Such systems are generally very expensive to replace. A need therefore exists, for an explosive detection apparatus or method which can be integrated into known types of airline baggage handling systems.
In some situations, for example the activities of police bomb squads or ordinance disposal teams, it is necessary to detonate and thereby neutralize explosive substances or explosive devices which are known rather than concealed. In some such cases, it is desirable to process large amounts of such substances or devices in a short periods of time with minimal risk to personnel and property. A need therefore exists, for an explosive detection method or apparatus which detonates known explosive substances and explosive devices either singly or in a batch load manner.